Method of manufacturing thin rubber articles



y 1942-. R. E. THOMPSON 2,283,238

METHOD OF MANUFACTURING THIN RUBBER ARTICLES Filed April 9, 1940Fetented May 19, 3%2

entree srsrss stones s hereunto rm enriches hey E. Thompson, Nyaclr, N.Y asslgnor to horicg llmhoretories line, Jersey @ity, N. .lL, e corporanew and useful improvements in the method of manufacturing sucharticles. The invention relates more particularly to improvements in theart of making sanitary elastic sheaths by the dipping process, thesheaths being formed by a sheath proper and a band integrally attachedthereto at its opening. In accordance with these improvements, elasticbands of predetermined size and elasticity may be provided at the openends of finger cots, thumb guards, rubber gloves, breast nipple sheaths,and other hollow elastic sheaths-of a similar nature, in which theopening is substantially smaller in cross-section than the sheathitself.

In sanitary elastic sheaths oi the kind contemplated, little. or noreliance is placed on the sheath proper for attachment to the body. The

sheath proper is merely intended to cover a part of. the body, anddepends essentially and primsrily on its built-in elastic band forattachment to the body. The band is alone sufllcient for the p se, andthis leaves the sheath free for its intended sanitary purpose. Thesheath protects the part covered from contamination by outside sources;and prevents contamination of other parts by the part covered. Thesheath is particularly useful in preventing loss or discharge Y ofmedication from the part covered to surrounding parts. The sheath isalso useful in functioning as a. cover and a support for a bandage orother cover placed over the aflected part. The sheath may contain anabsorbent, such as gauze, cotton, or the like, with or withoutmedication, for treating the port affected.

It is important that the opening of the hollow elastic articles besuitably reinforced. To accomplish this result, it is the practice insome cases to roll the elastic material at the opening into a. bead.While a roundbead of this kind is satisfactory for some purposes, it ishighly disadvantageous for others. For example, when the article istightly fitted over a part of the body, such as a. thumb, finger, wrist,breast nipple, etc., so as to be securely attached thereto, the rounded.bead tends to dig into the fleshin an uncomfortable and painful manner.It is also dimcult to control the elasticity of 2. rolled bead; the

larger the head in cross-section, the less readily,

it stretches. If, therefore, the bead is rolled to a.

size sumciently large to inhibit painful. digging into the flesh, itwill often lose its desired elasticity.

I have found that the disadvantages of the 19%, Serial No. 328,661

((Dll. 18- 58) rounded bead may for the most part be avoided byreinforcing the opening of the hollow article with an especially addedelastic band that is fiat orsubstantislly hat; and a band may beselected which will not painfully dig into the flesh and which will atthe some time remain securely attached to the body. Having decided on aband of optimum width, thickness and elasticity, the manufscturer may beassured that after the band is integrally attached to-the hollow elasticarticle at its opening, the band portion of the article will have thedesired characteristics.

The provision of an elastic band integrally attached to a hollow elasticarticle is, however, considerably complicated when the cross-section ofthe band is substantially smaller than the crosssectionel area. oi thehollow article. This is especially true of elastic sheaths or bass madeby the dipping process, in which the sheath has 29 an opening very muchsmaller in cross-section than the sheath proper. A form, having sub:stentially the size and shape of the article to be formed. is dippedinto a. suitable coating liquid. The coating remaining on the form mustbe removed, and therein lies the dimculty when the coating is to beintegrally secured to an elastic band. As a result of my investigations,I have discovered improvements in method and apparatus which make itpossible integrally to attach an an elastic band of predeterminedcharacteristics to a thin elastic hollow article at its opening.

The invention will be more fully understood by referring to theaccompanying drawing, taken in conjunction with the followingdescription, in 35 which:

Fig. 1 is a diagrammatic representation of a shaft, showing an elasticband suitably mounted around one end thereof, useful in a. practice ofthe invention;

2 is a. similar view, showing a head preliminarily mounted on the shaftof Fig. 1;

Fig. 3 is a view similar to Fig. 2, but showing the head and elasticband in final position on the shaft;

Fig. 4 is a view similar to Fig. 3, showing the head, elastic band andshaft assembly immersed in a body of coating liquid;

Fig. 5 is a, cross-sectional view 5-5 of Fig. 2;

Fig. 6 is a. cross-sectional view on theline 6-6 of Fig. 4;

Fig. '7 is a cross-sectional view of the assembly in part showing thehead, its coating and the band as a. unit separated from the shaft; and

Fig. 8 is a diagrammatic representation illuson the .line

-,fitted onto the shaft.

trating the removalof the elastic bag from the head.

Referring to Fig. 1, the apparatus shown comprises a shaft l0,preferably made of metal, such as aluminum, the head-end of which has atapered section H extending from the main body of the shaft to a taperedend or tip portion l2.

' This figure also shows an elastic band l3 suitably placed inapproximate position over the tapered r head-end of the shaft. The otherend I! of the shaft is threaded so as to be screwed in a base I5 and toaccommodate a lock nut Hi. This permits adjustment of the length of theshaft extending from the base.

Fig. 2 shows a head i1 having substantially the size and shape of thefinished article, in this case an elastic sheath several times larger incrosssectional area than the cross-sectional area of its opening. Thehead, like the shaft, is preferably made of metal, such as aluminum witha polished, smooth surface. As shown in this figure, the head is mountedover the tapered portion of the shaft in, and the head engages thenearest rim of the band l3.

In Fig. 3, the head is shown mounted in final position on the shaft. Asthe head is moved down the shaft, the head pushes the annular band downthe shaft into its final position. While this occurs, the rim of theband is and remains in contact with the head.

Referring to Fig. 4, the apparatus described is shown with the free endof the shaft extending upwardly and the head-end of the shaft, at leastso much of it as is covered by the head. and the band, submerged in abody of suitable coating liquid i8 confined in a container iii.

The construction of the head and shaft is shown more particularly inFigs. 5 and 6. The head is provided with a shaft-opening 20 adapted toreceive the head-end of the shaft. The fore portion 2! of theshaft-opening has a diameter substantially the same as body of theshaft,so that the head may be snugly The shaft-opening also contains a taperedportion 22 complementary to the tapered portion H of the shaft. Thebottom of the shaft-opening is a practically straight wall portion 23adapted to receive the tapered tip portion l2 of the shaft.

The shaft is provided with an air vent passageway 24 extending from thetip of the head-end of the shaft longitudinally through the centerportion of the shaft, and ending as an opening 25- in the side of theshaft at a distance sumciently. removed from the final resting place ofthe band; on the shaft so as not to be covered by coating liquid in thedipping process.

In the arrangement shown in Fig. 5, the head is preliminarily placedover the shaft and is brought in engagement with the rim of theannularband across the tapered portion ll of the shaft; whereas in Fig.6 the head and elastic band are shown mounted in final position on theshaft, with the headand part 0f.the band submerged in the coatingliquid.

The shaft is adapted to support the'elastic' band at the line ofjuncture 26 (see Fig. 6) between the two when the head is mounted on theshaft. The shape of the head is such that a snug fit is provided betweenthe head and shaft at the line of juncture, so that coating liquidcannot seepinto the shaft opening. The head and band rim are also inclose contact with one another so that coating liquid cannot penetrateto the shaft that of the main adhere thereto. of the head comessubstantially to a sharp line of intersection with the surface of theshaft opening in the head so that the edge 2] (see Fig. 8) effectivelypermits engagement with the rim of the band mounted on the shaft. Theband may then in turn be pushed forward on the shaft while frictionallysupported by the shaft.

. The surface 28 of the head at and near the entrance of theshaft-opening 20 tapers away from the shaft at an angle, preferably lessthan 90, sufficiently small to prevent a substantial build-up of rubberat the annular line of juncture 29 between the head and the elasticband, when the assembly is dipped in a body of coating liquid. With anangle of the degree contemplated, ex-

cess coating liquid may readily drain away from the band. If thereshould be a substantial buildup of rubber, it would of course alter theelasticity characteristics of the band portion of the sheath.

7 Fig. '7 shows the head, its adhering coating and the elastic band as aunit, from which the shaft has been separated or removed. The dottedoutline in the figure shows the position previously occupied by theshaft.

The apparatus may be used as follows in the practice of the invention.The annular elastic band I3, preferably of predetermined width,thickness and elasticity, is freely dropped over the tapered portions i2and ll of shaft ill. The internal diameter of the band is the same asthat of the sheath when finished, and is substantially the same as theoutside diameter of the shaft. When the band is dropped around the shaftin this manner, it engages the shaft frictionaily and assumes what maybe deemed a preliminary position.

The head H, which has the size and shape of the sheath proper, is thenfitted over the tapered portions l2 and ll of the shaft, as showninFigs. 2 and 5. The head engages the nearest rim of the elastic band,and as the head is pushed down the shaft, the When the head is broughtin final position on the shaft, that is, when it is securely attached tothe shaft, the head and band assume the position shown in Figs. 3, 4 and6, in contact with one another. During the mounting operation, airtrapped in the shaft-opening 20 is vented through the passageway 24 tothe outside atmosphere, in amount sumcient to prevent the building up ofpressure.

With the base end of the shaft extending upwardly, the head and band aresubmerged in a suitable coating liquid, such as liquid rubber latex,liquid rubber, or liquid rubber cement, etc. The head is permitted toremain submerged until a thin coating of the liquid adheres to the headand the outside of the annular band.

The shaft and head are then withdrawn from the body of coating liquid,and the entire assembly is preferably placed in a drying room maintainedat an appropriate temperature. If desired, and this is sometimes thepreferred practice, the shaft and head assembly is subsequently returnedfor another dipping in the coating liquid, so that a second coating maybe built onto the first coating; after which the shaft and head assemblyis again returned to the drying room. This procedure may of course befollowed as often as is necessary to produce a sheath of desiredproperties.

After the coating on the head and elastic band and has been suitablytreated in this manner, the

To this end, the outer surface I band is also moved along the shaft.

aaeaaee by grasping the head with one hand and the shaft with the other,and then pulling the two apart. Since the coating on the head isintegrally attached to the band, the coating and band remain with thehead as the shaft is pulled through and away from the band.

Since the band extends freely away from the head at its opening, asshown in Fig. 7, it provides a most important means for removing theresultant elastic sheath or bag from the head without injury to thesheath. The elastic band portion of the sheath is suitably stretchedinto an enlarged opening and the head is removed. One method of removingthe head from the sheath is illustrated in Fig. 8. The operator, forexample, places his'right thumb 3d at the base of the coated head, andinserts his right fore finger 3|, as well as his left fore and middlefingers 32 and 33, into the interior of the annular band in any desiredorder. The three fingers are pulled apart and shoved deeper into theinterior of the sheath as it separates from the head. The elastic bandportion of the sheath is stretched in this manner until the opening issuiiiciently large to permit the expulsion of the head therethrough.This is accomplished by shoving the thumb 30 toward the fingers.

Special precautions are taken to remove stickiness from the inside andoutside surfaces of the sheath. To this end, the head, coating and band,

assembly, as shown in Fig. 7 with shaft removed, is dropped into a bodyof suitable powder, such as talcum or other appropriate material.wellknown to the art. The powder promptly removes the stickiness fromthe outside surface of the coating. The operator then grasps theassembly, as shown in Fig. 8, and expels the head through the enlargedopening of the elastic band portion, preferably while the entireassembly is under the powder. As the head is propelled through'theenlarged opening, the sheath is turned inside out, thus assuring contactof powder with both sides of the sheath.

The sheaths are then picked out of the powder, shaken to remove excesspowder and are appropriately packaged. If imperforate sheaths aredesired, it is advantageous to test for pin holes by blowing them upwith a certain amount of air.

I claim:

1. In the method of manufacturing elastic bags by the dipping process,the bag being, formed of a bag proper and a band integrally attachedthereto at its opening, and the opening being substantially smaller incross-section than the interior of the bag when both are unextended, thesteps which comprise placing an elastic band about one end of the shaft,mounting a head having substantially the size and shape of the bagproper on said end of the shaft, bringing the head in final position onthe shaft in contact with the nearest rim of the band, with the oppositeend of the shaft extending upwardly dipping the head downwardly into abody of coating liquid up and onto the elastic band to form a thincoating over the head and onto and adhering to the band, and removingthe resulting elastic bag with the elastic band integrally. attachedthereto from the head.

2. In the method of manufacturing elastic bags by the dipping process,the bag being formed of thereto at its opening, and the opening beingsubstantially small in cross-section than the interior of the bag whenboth are unextended, the steps which comprise placing an elastic band ofsubstantially the size of the opening about a shaft having a diametersubstantially as large as the opening of the bag, mounting a head havingsubstantially the size and shape of the bag proper onto the head-end ofthe shaft, bringing the head in final position on the shaft in contactwith the rim of the band -on the shaft, with the opposite end of theshaft extending upwardly dipping the head downwardly into a body ofcoating liquid up and onto the elastic band to form a thin coating overthe head and onto and adhering to the band, withdrawing the shaft andhead with its adhering coating from the body of coating liquid,separating the head together with its coating and the bandintegrallyattached thereto as a unit from the shaft, suitably stretching theelastic band portion of the resulting elastic bag on the head into anenlarged opening, and removing the bag from the head by passing the headcompletely through the enlarged opening.

3. Method according to the preceding claim, in which the resultingelastic bag is treated to, remove stickiness directly before andafterthe head is passed through its opening.

4. In the method of manufacturing elastic bags by the dipping process,the bag being formed of a bag proper and a band integrally attachedthereto at its opening, and the opening being substantially smaller incrosssection than the interior of the bag when both are unextended, thesteps which comprise placing an elastic band of substantially the sizeof the opening about a shaft having a diameter substantially as large asthe opening of the bag, mounting a head having substantially the sizeand shape of the bag proper and a rounded outer surface comingsubstantially to a sharp angular line of intersection with the surfaceof the shaft onto the head-end of the shaft, bringing the head in finalposition on the shaft in contact with the nearest rim of the band on theshaft, with the end of the shaft extending upwardly dipping the headdownwardly into a body of coating liquid up and onto the elastic band toform a thin coating over the head and onto and adhering to the band,withdrawing the shaft and head with its adhering coating from the bodyof coating liquid, draining excess coating liquid from the annular bandand the head to prevent excessive build-up of coating material at theline of Juncture between the two, separating the head together with itscoating and the band integrally attached thereto as a unit from theshaft, suitably stretching the elastic band portion of the resultingelastic bag on the head into an enlarged a bag proper and a bandintegrally attached opening, and

removing the bag from the head by passing the head completely throughthe enlarged opening.

5. In the method of manufacturing elastic bags by the dipping process,the bag being formed of a bag proper and a band integrally attachedthereto at its opening, and the opening being substantially smaller incross-section than the interior of the bag when both are unextended, thesteps which comprise placing an elastic band of substantially the sizeof the opening about a shaft having avdiameter substantially as large asthe opening of the bag, mounting a head having substantially the sizeand shape of the bag proper and a shaft opening extending into theinterior thereof onto the head &

end of the shaft,

I bags by the dipping pushing the elastic band with theheadalong theshaft while the head is being tightly fitted thereon, so as to leave thehead in effective contact with the nearest rim of the band, with the endof the shaft extending upwardly dipping the head downwardly into a body'of coating liquid up and onto the elastic band to :fqrm a thin coatingover the hand and onto and adhering to the band, withdrawing theadhering coating from the body of coating liquid, separating the headtogether with its coating and the band integrally attached thereto as aunit from the shaft, suitably stretching the elastic band portion ofhead into an enlarged opening, and removing the bag from the head bypassing the head completely through the enlarged opening.

shaft andhead with its v the resulting elastic bag on the 6. In themethod 01' manufacturing elastic process, the bag being formed of a bagproper and a band integrally attached thereto' at its opening, and the:opening being substantially smaller in cross-section than the interioror the bag when both are unextended,

the steps which comprise placing an elastic band of substantially thesize 'of the opening about a shaft having'a diameter substantially aslarge as the openin of the bag proper and an air vent passageway,mounting a head having substantially the size and shape .of the bagproper and a shaft opening extending into the interior thereof onto thehead-end of the shaft, bringing the head in final position on the shaftin contact with the-nearest rim of the band, venting air from the shaftopening in the head through said air vent passageway so that airpressure within the shaft opening is not set up to oppose tightening ofthe head on the shaft, dipping the head downwardly into a body ofcoating liquid up to and onto the band to form a thin coating around thehead and onto and adhering to the band,

withdrawing. the shaft and head with its adhering coating from the bodyof coating liquid, separating the head together with its coating and theband integrally attached thereto as a unit from the shaft, suitablystretching the elastic band portion of the resulting elastic bag on thehead into an enlarged opening, and removing the bag from the headbypassing the head completely through the enlarged opening.

- ROY E. THOMPSON.

